Disable rent fees collection

Summary

Add a new feature to disable rent fees collections.

Motivation

On solana network, (Rent) [https://solana.com/docs/intro/rent] was introduced to account for the storage costs of an account initially. However, as the disks become cheaper and cheaper. The cost of storing the account becomes negligible.

Furthermore, today it is no longer possible to create any new rent-paying accounts on the network. Any attempt to create a rent-paying accounts will result a transaction error. The total number of rent-paying accounts on solana network is phasing out. Therefore, when all the rent-paying accounts are gone in the network, we would like to disable rent fee collection on the network completely through a feature.

Alternatives Considered

None

New Terminology

None

Detailed Design

When the feature "disable rent fees collections" is activated, rent will no longer be collected from accounts, nor will the collected rent fees be distributed to validators.

Note that this does not change the requirement that existing rent-paying accounts need to be made rent-exempt first, before any withdrawals can be made, should there be any such rent-paying accounts.

Impact

The main impact of this SIMD is to simply the validator design. Rent collection code is a non-trivial piece of code inside the bank. By removing it, we simply the overall code of bank, and we no longer need to maintain it in existing validator client code. This will also help to simplify the development of other validator client implementations, which don't need to replicate the rent collection logic.

Security Considerations

There will be no more rent-paying accounts before this feature is activated. It is already impossible to create any new rent-paying accounts on the network, there should be no security issues. However, if for some reason rent-paying accounts still exist or are created in the network, when the feature is activated, the network will still work as expected. The only difference is that rent fees will no longer be collected or distributed.

Backwards Compatibility

Incompatible.